Air screw hub



, H. N. WYLIE 1,830,731

AIR scREw HUB Filed Jan. 24, 1930 4 Sheets-Sheet l NOV. 3, 1931.

H. N WYLIE AIR SCREW HUB Filed Jan. 24. 195(3- 4 Sheets-Sheet 5 InventorH. N. WYLlE AIR SCR W HUB Nov. 3, 1931.

Filed Jan 4 Sheets-Sheet 4 Patented Nov. 3, 1931 UNITED STATES PATENTOFFICE HAMILTON NEIL WYLIE, OF COVENTRY, ENG-LAN D, A SSIGNOR TO sm W.G. ARMSTRONG WHIIWORT'H AIRCRAFT LIMITED, COVENTRY, ENGLAND AIR SCREWHUB Application filed January 24, 1930, Serial No. 423,190, and in GreatBritain February 4, 1929.

This invention relates to air screws of, the kind in which the bladesare universally pivoted to the hub so that they are relieved of allbending stresses, and its main object is to provide simple and effectiveconstructions of small weight. Subsidiary objects are to provide foradjustment of pitch of-the blades simultaneously and/or separately andto ensure that centrifugal force exerts no tendency to change the pitch.

According to this invention, the hub is formed with a pair ofprojections provided with bearings for trunnion-like members on a yoketo which a: blade is pivoted about an axis transverse to that of thetrunnion-like members, so that the blade is universally pivotedbutcannot twist as a whole in relation to the hub.

If a number of blades is supported in this Way from a pair of spacedplates constituting the projections, and if either or both of theseplates is pivotally mounted on the hub for rotation about its main axis,by twisting the one plate in relation to the other all the yokes can berocked to adjust the bladesv simultaneously as regards their pitch.

Preferably, the yoke of a' blade is tiltable about either trunnion-likemember so that the blade may be moved either to adjust its pitch or thedistance of its centre of gravity from the axis of the hub; and in apreferred arrangement for effecting this means (such as eccentricbearings in the projections) are provided for adjusting thetrunnion-like members in relation to the projections.

In the accompanying drawings,

Figure 1 is a diagrammatic end view of the hub of a two-bladed propellerembodying one application of the invention, I

Figure 2 is a side view of a hub for a three'' bladed propeller showinga further application of the invention,

Figure 3 being an end view thereof with certain parts in section andbroken away for clearness,

Figure 4tis an end view, partly in section, of a hub for atwo-bladedpropeller illustrating an alternative method of mounting the blades,

Figure 5 being a fragmentary side elevathe universal attachment of theother blade being shown separated from one another and 69 in positionfor assembly, and

Figures 8 and 9 are respectively diagrammatic side and end views of atwo-bladed propeller illustrating two relative movements between theblades and the hub.

In the construction shown in Figure 1, the hub 2 is formed at pointsdiametrically opposite one another with two tangential flat cheeks 3,each with a radial stem 4 which forms a pivot. On each of these pivotsis mounted, free to turn, a plate 5. The plates are therefore spacedand, as they are arranged to project at each end beyondthe outsidediameter of the hub they form a pair of pr0- jections 50 on each side ofthe hub, and each projecting end is formed with an eye 6 or bearing toreceive the end of a trunnion-like .member. This, in its simplest form,is a yoke 7 formed at or near its centre with an enlargement 8 which isbored transversely at 9 to form a bearing or pivot to which the end v10of the blade 11 is pivoted.

Thus the axis of each blade can move universally but 'it cannot twist.

The projections 50 may be fixtures but preferably they are constitutedby pivoted plates 5 as shown, and means may be provided whereby oneplate can be moved angularly about its pivot in relation to the otherplate,

0 to vary the p1tch'of both blades s1multaneous- 9 1y. In theconstruction shown, each plate is movable angularly about its pivot andcan be locked in the desired position by the bolts 12 which extendthrough curved slots 13 in each plate and into the flat cheeks 3. Tovary the pitch of one blade 11 in relation to the other, thetrunnion-like members 14 on eachyoke 7 may be movable separately inrelation to their plates. For example they may be mounted in eccentricbushes 15 in the plates, as more fully described later.

It is not essential that the projections 50 be tangential to the axis ofthe hub, and in some cases they may be perpendicular and transverse tothe axis thereof, an example of which is shown in Figures 2 and 3, foruse with a three-bladed propeller. In this the forward plate 5, i. e.,that one on the right of Figure 2, is preferably integral with the shellof the hub 2 and is substantially in the form of a triangular flange(Figure 3). The back plate 5 (on the left of Figure 2) is of similarshape but is formed separately from the hub and is free to rotateslightly thereon. Thus the corners of the plates, which are spaced, formthree pairs of projections, one pair for each blade.

In each corner of each plate is formed the eye 6 in which is held onetrunnion-like member 7. For this purpose, in each eye is mounted a splitbush 15 the interior of which is eccentric to the exterior, and in thebush fits the trunnion member 14. By simultaneously adjusting theeccentric bushes at each end of a yoke, the centre of gravity of theblade attached thereto can be radially moved, which is useful forbalancing the complete propeller.

Preferably, the trunnion-like members 14 are} parti-spherical and thebushes 15 are in the nature of cups engaged by the partisphericalportions. The bushes consequently require to be split and to secure themin position they are provided at one end with a shoulder 16, which maybe conical, and are threaded through the correspondingly coned eyes 6from the inner side of the plates and secured in positionby nuts 17screwing on the ends of the bushes projecting through the outer sides ofthe plates. The nuts are subsequently locked by a tab washer. 18 andgrub screws 19. On slacking off a nut, the corresponding bush can berotated.

The provision of the ball and socket mounting just described for thetrunnion-like members is to allow the yoke to be moved about eithertrunnion member to adjust the pitch of the corresponding blade.Furthermore this arrangement enables all the trunnion members to bemoved sideways at one end to vary the pitch of all the bladessimultaneously by moving the back plate around the axis of the hub.

Preferably some resilient material 20 is interposed, as'shown, betweenthe hub 2 and -'-the part of the yoke adjacent the hub, or it trunnionmembers without difliculty. When in position the bolts of the strap areslackened so that the resilient pads press the surfaces of the strapagainst the end faces of the jaw members. In this way'a resilientsupport is provided to the blades which resists slightly, in the mannerrequired, their free pivotal movement.

A convenient method of adjusting the angularity of the movable plate inrelation to the fixed one is to provide one or more tangential screwdevices 21 (Figure 3) on the hub and acting upon the movable plate orsome part or parts carried thereby, such as the nuts 17, or vice versa.Alternatively, no actual adjusting device need be provided, but, afterall the trunnion members have been set exactly alike, or after all theblades have been set to the same pitch and the propeller balanced,radial holes would be drilled through a flange, not shown, on theinterior of the movable plate and into the hub to receive a dowel,setscrew, or the like, which would thereby ensure accurate setting andlocking of the movable plate and all the blades to a certain pitch.Other holes could be made with the plate moved through certain anglesfrom the first position, corresponding to minute variations of the pitchof the blades, say half a degree.

Thus. when the hub is dismantled, it can easily be accuratelyre-assembled without likelihood of the blades being of different andinaccurate pitches, and the partsv can easily be set so as to providefor known variations of pitch.

In the alternative arrangement shown in Figures 4-9, the blade 11 isattached to an adaptor 22 which consists of a socket of circular boreand circular periphery near the closed end 23. In the sides of this partare formed two diametrical holes 24 opposite to one another and adaptedto receive therein a pin 25 to be more fully described later. At rightangles to these holes elongated slots 26 are formed in the sides andparallel to the axis of the socket and adapted to receive transversely ayoke member 27 more fully described hereunder. adaptor consists of twoflat plates 28 parallel to the axis of the socket, and-at an angle-which may be about degrees to the slots 26 and to the holes 24. Theseplates are 111- timately securedto the root of the propeller blade byrivets or other means.

Fitted into the socket is a compression piece 29 which is in the form ofa jaw with holes 30 transverse to the jaws and at right angles to theslot 31 between them. Through these holes 30 the pin 25 above referredto is ultimately fitted, and, when the compression piece is in position,the holes 30 are in line with holes 24 in the adaptor. The holes 30 areof the same diameter as the part of the pin 25 which engages them, butthe holes The other end of the 24 in the adaptor are larger than thepart of the pin which lies in them. 1

When the compression piece 29 is in position in the'adaptor the yoke 27is then passed through the slots 26 in the adaptor and lies in the slot31 in the compression piece.

This yoke consists of a fiat block of metal with a trunnion 32 at eachside. The flat central portion lies in the slot 31, and each trunnion 32projects with clearance through one of the slots 26 inthe adaptor. Inthe flat centreis a transversely bored hole 33 which registers with theholes and 24 in the compression piece and adaptor respectively and isarranged to receive the pin 25.

The latter is for the most part a plain cylindrical rod with a bearingfit in the holes 30 and 33 and terminating in reduced ends 34 which arescrew-threaded at 35. The reduced parts 34 have a clearance in the holes24 in the adaptor,- and the clearance may be rendered still greater byforming flats 36 opposite to one another. This clearance is to enablethe adaptor 22 to be moved angularly over a small range relative to theyoke 27, compression piece 29 and in 25 in order to vary the pitch ofthe blade without varying the distance of the centre of gravity of theblade from the axis of rotation. Between the nuts 37 screwing on the pinends and the outsides-of the adaptor are arranged saddle-shaped washers38 which grip the sides of the adaptor when the nuts are tightened upand lock the parts in the desired angular position. Index marks 39 maybe provided on the relatively adjustable parts so that pitch setting maybe known.

The ends of the trunnions 32 are'screwthreaded at 40, and between thescrew-threaded ends and the block are parallel plain portions which takebearings in the projections 50 on the hub. These projections take theform of radially arranged lugs diametrically opposite one another andtwo on each side of the hub. in the case of a two-bladed propeller. Fora three-bladed propeller there would be three pairs of lugs at 120degrees. For convenience in fitting, the hub is split transversely at41, each part carrying a pair of the diametrically opposed projectinglugs 50,

each with a hole 42 to receive the plain bearing portions on the yoketrunnions. The two parts of the hub are dowelled together or otherwiselocated angularly, and are held in position by the means which securethe hub upon the propeller shaft, not shown.

The mouth of the bore in the adaptor is finally closed bv a stiffener 43which consists of a disc or plug which is riveted in the socket andformed with a diametrical web which projects along the adaptor-between theplates 28 for any suitable distance to impart stiffness to them.

Each blade 11 is thus universally-jointed to the propeller hub 2,movement in one direction causing the pin 25 to twist in the yoke, andmovement at right angles resulting in the yoke swivelling about theprojections 50 on the hub. To hold the blade approximately radially tothe hub axis there is interposed between the closed end 23, of theadaptor and the periphery of the hub a resilient pad 44 attached to asaddle-shaped piece 45 which in turn is secured to the end of theadaptor.

The invention thus provides for two relative movements between the bladeand the hub, which are illustrated diagrammatically in Figures 8 and 9,these-being,-tilt, which is inclination of the blades 11 forwards orbackwards in an axial direction and indicated by the angle X in Figure8, and lag, which is inclination of the blades 11 about the hubprojections from a truly radial position and indicated by the angle Y inFigure 9. The blades can, therefore, adjust themselves quite freely. Itis, however, very important that the centre of gravity of the two bladescombined should lie on the axis of the hub, and this entails that thelag angle Y of the two blades must be identical; that is to say, theangle which the blades take up about the axis of the trunnions in thehub projections in relation to radii from the hub axis passing throughthe trunnion axis.

xii)

running. Also it is possible to see exactly a the pitch angle to whichthe blade or blades is set.

What I claim as my invention and desire to secure by Letters Patent ofthe United..

blade of the air-screw to said yoke about an axis transverse to the axisof said trunnionlike members.

2.In an air-screw, the combination with yoke and said socket aboutanaxis transverse to that of said trunnion-like members.

3. The combination claimed in claim 2, in

which the trunnion-like members and transverse pivot in the yoke extendthrough opposite sides of the socket with clearance to allow of varyingthe pitch of the blade.

4. In an air-screw, the combination with a hub, a yoke havingtrunnion-like members, saidmembersbeingcarried in bearings in saidprojections, a socket receiving said yoke and fitting within saidprojections, said socket having a blade of the air-screw secured thereto, and means pivotally interconnecting said yoke and said socket aboutan 'axis transverse to that of said trunnion-like members, saidtrunnion-like members and transverse pivot in the yoke extending throughopposite sides of the socket with clearance to allow of varying thepitch of the blade, the yokes of each blade being interconnected formovement in unison to ensure uniform angles of lag.

5. An air-screw comprising a hub having a pair of projections extendingtherefrom, an

, ada tor housed between said projections and having a socket thereinand having elongated aligned slots in opposite sides thereof openinginto said socket, said adaptor also having aligned holes in oppositesides thereof at right angles to said slots, a yoke fitted into saidsocket and having trunnion-like members projecting into said slots,means for connecting said adaptor to said projections, and means forpivotally connecting said yoke a and said adaptor about an axistransverse to that of said trunnion-like members.

In testimony whereof I aflix my signature.

HAMILTON NEIL WYLIE.

